The present invention relates generally to devices and methods for collecting and filtering biological suspensions. More specifically, the present invention relates to containers and methods for filtering bone marrow.
Bone marrow transplantation is used to treat a variety of hematological diseases. It is an accepted mode of therapy for a plastic anemia and immunodeficiency diseases. Additionally, bone marrow transplantation has been used experimentally to treat disorders such as refractory leukemias, metabolic diseases, congenital anemias, and malignancies.
Typically, bone marrow is removed in a sterile operating field using syringes and special aspiration needles while the donor is under general anesthesia. The marrow is collected from the sternum or iliac crest of the donor. The harvested marrow is then placed into a container and mixed with an anticoagulant solution.
After the marrow has been collected and combined with an anticoagulant, the mixture is then passed through two or more filtering devices to remove large particulate such as fat, bone chips, and/or clots. Originally, such filtering devices were xe2x80x9chomemadexe2x80x9d devices, for example, created using sawed-off glass or syringes to which wire screens were attached. After being filtered, the bone marrow cells are collected in a blood transfer pack unit and then transferred to the recipient or further processed per institutional procedure.
A few years ago, a bone marrow kit was developed by Baxter Healthcare Corporation, Deerfield, Ill. (a wholly owned subsidiary of the assignee of the present invention). The Fenwal Bone Marrow Kit, Code 4R2104, consists of a collection bag, three disk-shaped, rigid, stainless steel filters (500, 300, and 200 xcexcm sizes), and a final collection bag for the processed marrow. The kit allows users to perform the bone marrow processing methods set forth above in a standardized system that is sterile, disposable, and easy to use.
At times, it is possible for the filters in a bone marrow kit to become plugged due to bone chips, fat, and other cellular materials. Because of the rigid construction of the inline filter, it is necessary for the filter to be removed from the system and then flushed to remove the material plugging the filter. When this occurs, there exists a potential for contamination and loss of cells. Additionally, flushing the system has the additional disadvantage that it can dilute the marrow.
The present invention provides an improved bone marrow kit. Additionally, the present invention provides an improved container having an inline filter that can be used in systems for filtering biological suspensions. Further, the present invention provides an improved method for making an inline filter as well as a method for collecting bone marrow.
To this end, in an embodiment, the present invention provides a bone marrow kit comprising a collection container having flexible walls defining an interior for receiving a bone marrow containing fluid having an inlet opening and an outlet opening and including a prefilter that extends from the outlet opening into the interior of the container so that fluid must flow through the prefilter to exit the container through the outlet opening. At least a first inline filter member is provided that is coupled to the outlet opening of the collection container, the first inline filter member having a flexible plastic body that defines an interior, an inlet opening, and an outlet opening. The interior includes a filter so constructed and arranged that fluid that enters the inlet opening must flow through the filter to exit the first inline filter member through the outlet opening. A container is provided for receiving a filtered bone marrow containing fluid having an interior in fluid communication with the outlet opening of the first inline filter member.
Due to the flexible nature of the walls that define the bodies of the collection container and the inline filter, the walls can be manipulated if desired during the filter process. This allows one to manipulate the filter through the walls allowing cells trapped in the filter to be dissolved.
In an embodiment, a second inline filter member is coupled to an outlet opening of the first inline filter member. The second inline filter includes a flexible plastic body that defines an interior, having an inlet opening and an outlet opening. The interior includes a filter so constructed and arranged that fluid that enters the inlet opening of the second inline filter member must flow through the filter to exit the outlet opening of the second inline filter member. The outlet opening is coupled to an inlet opening of the container for receiving the filtered bone marrow containing fluid.
Preferably, the prefilter of the collection container extends from the outlet opening into the interior of the container for a distance sufficient to allow bone chips, large fatty deposits, and clot-like fibrin materials to sink to a bottom portion of the container, while still allowing fluid to flow through the filter when the bone marrow containing fluid is received within the collection container. In a preferred embodiment, the prefilter includes a rigid frame that supports a flexible filter member.
In an embodiment, the present invention provides a collection container for collecting a biological suspension to be filtered comprising a flexible body defining an interior having an inlet opening and an outlet opening. The container includes a filter including a rigid frame, having a screen secured therearound, extending from the outlet opening into the interior for a distance sufficient to allow at least some particulate to settle on a bottom of the interior and allow fluid to still flow through the screen. The filter is so constructed and arranged so as to filter fluid that enters the interior prior to the fluid entering the outlet opening. In a preferred embodiment, the screen is constructed from a fluorocarbon plastic.
In an embodiment, the present invention provides, an inline filter for filtering biological suspensions comprising a body defined by flexible sheets of plastic sealed along edges thereof to form an interior having an inlet and an outlet opening. The inline filter includes a filter comprising a screen that is sealed along the edges of the sheets so as to extend across and for an entire length of the interior and divide the interior into a first section and a second section, the screen being so located that the inlet opening is in the first section and the outlet opening is in the second section and fluid entering the interior from the inlet must flow through the screen prior to entering the outlet opening.
Additionally, the present invention provides a method for manufacturing an inline filter comprising the steps of: placing a screen between two sheets of a plastic material; sealing the sheets of plastic together. along edges thereof to create a seal line having a width and defining an interior between the sheets that is divided into two sections by the screen, a perimeter of the screen extending into a width of the seal line between the sheets of plastic so that the screen extends across the entire area of the interior, the screen being located, however, so that it does not extend across the entire width of the seal line; and locating an inlet and an outlet on opposite sides of the screen.
Further, the present invention provides a method for filtering a bone marrow containing fluid comprising the steps of: collecting a bone marrow containing fluid in a collection container having flexible wall members that define an interior and a prefilter extending from an outlet opening of the container into the interior of the container; allowing bone chips, large fatty deposits, and clot-like fibrin materials to collect at a bottom portion of the interior of the collection container while allowing fluid flow through the prefilter and into the outlet opening of the container; passing the fluid from the outlet opening of the container through an inline filter member having a flexible body defining an interior having an inlet and outlet opening and a screen located within the interior between the inlet and outlet opening for filtering fluid that enters the inlet before it enters the outlet opening; and collecting the filtered fluid from the outlet opening of the inline filter member.
Additional features and advantages of the present invention are described in, and will be apparent from, the detailed description of the presently preferred embodiments and from the drawings.